Systems and methods of tissue closure

ABSTRACT

Apparatus, systems, and methods are described for closing the base of a left atrial appendage or other tissue structure. A tissue closure device comprises a pair of legs having compliant surfaces for engaging against opposite sides of the tissue structure. A plurality of axially spaced-apart tissue-penetrating fasteners are delivered from one leg to the other to pierce the intervening tissue and hold the closure device in place on the tissue structure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/180,373 (Attorney Docket No. 34814-703.401, U.S. Pat. No. ______),filed Jul. 11, 2011, which is a divisional of U.S. application Ser. No.11/744,135 (Attorney Docket No. 34814-703.201, U.S. Pat. No. 7,992,757),filed May 3, 2007, which claims the benefit of priority from U.S.Provisional Application No. 60/797,461 (Attorney Docket No.34814-703.101), filed May 3, 2006, the contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to medical devices, systems, andmethods. More particularly, the present invention relates the closureand removal of a left atrial appendage or other tissue structure using acompliant compression body for isolating the structure near its base.

Atrial fibrillation is a relatively common condition characterized by avery rapid heart beat of the left and right atrium. While atrialfibrillation is not normally fatal itself, it has been associated withan increased risk of stroke. It is believed that the rapid heart beatcauses blood to pool in the left atrial appendage which causes embolithat are released into the left atrium from where they can enter thecerebral vasculature, thus causing a stroke. In addition to stroke, theemboli can enter coronary circulation, potentially causing myocardialinfarction, or can enter peripheral circulation, potentially causingperipheral vascular disease.

The risk of stroke in patients suffering from atrial fibrillation can bereduced in a variety of ways. For example, blood thinning drugs can beused to reduce the risk of clot formation. The use of blood thinners,however, is contraindicated in patients at risk of bleeding disorders.

More aggressive treatment protocols have been proposed which involveclosing the left atrial appendage. Closure and excision may be performedin open surgical procedures, typically requiring the patient to beplaced on by-pass and the chest to be opened through the sternum.Alternatively, thoracoscopic and other less invasive procedures havebeen proposed. U.S. Pat. No. 5,306,234 teaches the performance ofbeating heart procedures using otherwise conventional surgicaltechniques. The use of conventional techniques through small chestpenetrations while the heart is beating can be difficult to perform.U.S. Pat. No. 5,865,791 describes an intravascular approach where toolsare introduced through the vasculature and passed into the left atrium.The tools are used to ablate or fuse the left atrial appendage from theinside using energy, adhesives, or the like. The '791 patent alsodescribes a thoracoscopic procedure where a tether is placed over theneck of the atrial appendage and tied off to achieve isolation. The '791patent still further suggests other closure elements including sutures,staples, shape-memory wires, biocompatible adhesives, and the like. U.S.Pat. No. 6,488,689 describes a transpericardial procedure where thedistal tip of the left atrial appendage is grasped and pulled backwardlythrough a capture loop which encircles the base of the left atrialappendage.

For these reasons, it would be desirable to provide improved apparatus,systems, and methods for less invasively closing the left atrialappendage and other body structures. Such apparatus, systems, andmethods should be capable of being performed on beating hearts, shouldavoid the need to form a transeptal penetration to access the leftatrium, and very importantly should result in tissue closure at the baseof the left atrial appendage. In addition to the above, it would bestill further desirable if the methods and protocols were relativelyeasy to perform and the closure element and other aspects of the deviceproduce a secure closure. At least some of these objectives will be metby the inventions described herein below.

2. Description of the Background Art

Less invasive and other procedures for closing the left atrial appendageare described in U.S. Pat. Nos. 6,488,689; 5,865,791; and 5,306,234; andPublished Application Nos. 2005/0154404 and 2004/0030335. Other tissueligation tools and techniques are described in U.S. Pat. Nos. 6,790,172;6,436,108; 6,051,003; 5,624,453; 5,507,797; and 4,257,419.

BRIEF SUMMARY OF THE INVENTION

The present invention provides alternative and improved apparatus,systems, and methods for closing a tissue structure. Embodiments of thepresent invention provide a tissue closure device that includes acompression body with two opposing compliant surfaces for engagingeither side of the tissue structure. The compliant surfaces preferablyhave a softness matching that of the tissue structure. The closuredevice preferably have a flexibility and dynamic performance similar tothat of the tissue structure. Fasteners are disposed in the compressionbody adjacent the opposing compliant surfaces and at least onetissue-piercing fastener is configured to emerge from a first compliantsurface, pass through the intervening tissue at a puncture site to thesecond compliant surface, and securely engage a second fastener compressthe tissue between the two surfaces. An open well may be disposed ineither or both of the compliant surfaces around the puncture site wherethe tissue-piercing fastener passes through the intervening tissue tocreate a gasket seal around the puncture site. A stabilizing lip may beprovided on one of the compliant surfaces such that one surface islarger than the other surface. Vacuum ports may also be provided in thecompliant surfaces to engage the surface of the tissue structure.Fasteners of the closure device may include open lumens or recesses forinteracting with a device applicator used to install the closure device.

Embodiments of the present invention provide a system for tissue closurethat includes a tissue closure device and a device applicator used toinstall the device. The applicator may include two opposing jaws orprongs used to hold open two opposing legs of the closure device, and tobring the legs together to engage the fasteners and install the device.An alignment comb may be used having studs that engage each one of thefasteners in the closure device. The alignment comb may be receivedwithin inner jaws of the applicator which may be moved independently ofthe outer jaws to release the closure device after installation iscomplete. Vacuum lumens may be provided in each of the jaws thatcommunicate with the vacuum ports of the closure device to providesuction to the ports. The jaws or probes may move in a parallel mannerwith respect to each other or may move about a pivot point. Theapplicator may include a handle mechanism for actuating the movement ofthe jaws.

Embodiments of the present invention provide a method for implanting atissue closure device about the base of a left atrial appendage (LAA).The procedure may be performed thoracoscopically using a thoracoscopeintroduced in the region above the LAA after the left lung has beendeflated. The procedure can be performed under direct vision through thesame incision through which the applicator is introduced or through aseparate incision formed over the region of the LAA. The tissue closureapplicator is introduced intercostally, the probes are then spreadapart, spreading the legs of the closure device. After the legs arelocated on opposite sides of the LAA, the legs will be presseddownwardly on to the cardiac tissue surrounding the base of theappendage. The vacuum may then be optionally applied through the legs ofthe closure device, adhering the legs to the cardiac surface. After theproper position is visually confirmed, the applicator will bemechanically closed over the base of the LAA. The applicator may then betriggered to deliver the male fasteners into the female fasteners. Thetissue closure applicator may then be disengaged from the installedclosure device.

Further aspects and advantages of the present invention will be apparentin view of the following detailed description of the preferredembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of one embodiment of a tissue closureapplicator constructed in accordance with the principles of the presentinvention. An exemplary tissue closure device is shown in broken linemounted on the distal end of the tissue closure applicator.

FIG. 2 is an isometric view of one embodiment of a tissue closure deviceconstructed in accordance with the principles of the present invention,shown with a middle section broken away.

FIG. 3 is a top plan view of the tissue of closure device of FIG. 2.

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 3.

FIGS. 5A and 5B illustrate the fastener structures of the tissue closuredevice of FIGS. 2-4, shown in an unengaged configuration (FIG. 5A) andin an engaged configuration (FIG. 5B).

FIG. 5C shows a female fastener which is able to accommodate differenttissue thicknesses.

FIG. 6 is a top plan view of another embodiment of a tissue closuredevice constructed in accordance with the principles of the presentinvention.

FIG. 7 is a top plan view of another embodiment of a tissue closuredevice constructed in accordance with the principles of the presentinvention.

FIG. 8 is a top plan view of another embodiment of a tissue closuredevice constructed in accordance with the principles of the presentinvention.

FIG. 9 is a detail of the distal end of the tissue applicator device ofFIG. 1.

FIG. 10 is a detailed view of the distal end of the tissue closuredevice of FIG. 1, shown with a portion broken away and with theactuation mechanism exposed.

FIG. 11 is a detailed view of the device actuation mechanism taken alongline 11-11 of FIG. 10.

FIG. 12 illustrates another actuation mechanism for the tissueapplicator of the present invention.

FIG. 13 is a top plan view of the embodiment of FIG. 12, shown with theopen configuration in full line and in a closed configuration in brokenline.

FIGS. 14, 15, 16, and 17 illustrate use of the apparatus of the presentinvention for implanting a tissue closure device about the base of aleft atrial appendage in accordance with the principles of the presentinvention.

FIG. 18 is an isometric view of one embodiment of a tissue closuredevice constructed in accordance with the principles of the presentinvention.

FIG. 19 is an elevation view of the tissue closure device of FIG. 18.

FIG. 20 is cross-sectional view of the tissue closure device along lineA-A of FIG. 19.

FIG. 21 is an isometric rear view of the male fastener.

FIG. 22 is an isometric front view of the male fastener.

FIG. 23 is a cross-sectional view of the male fastener.

FIG. 24 is an isometric rear view of the female fastener.

FIG. 25 is an isometric front view of the female fastener.

FIG. 26 is a cross-sectional view of the female fastener.

FIG. 27 is an isometric view of the alignment comb constructed inaccordance with the principles of the present invention.

FIG. 28 is a detailed view of the comb stud.

FIG. 29 is an isometric view showing the alignment comb engaged with themale fasteners of a closure device.

FIG. 30 is an isometric view showing the alignment comb disengaged fromthe male fasteners of a closure device.

FIG. 31A is a cross-sectional view of another embodiment of the tissueclosure device constructed in accordance with the principles of thepresent invention.

FIG. 31B is a top plan view of the tissue closure device of FIG. 31A.

FIG. 31C is a top plan view of another embodiment of the tissue closuredevice constructed in accordance with the principles of the presentinvention.

FIG. 31D is a top plan view of another embodiment of the tissue closuredevice constructed in accordance with the principles of the presentinvention.

FIG. 32 is an elevation view of another embodiment of a closure deviceapplicator constructed in accordance with the principles of the presentinvention.

FIG. 33A is an elevation view showing the jaws of the applicator open toreceive the closure device.

FIG. 33B is an elevation view showing the jaws of the applicator closedto install the closure device.

FIG. 33C is an elevation view showing the inner jaws moving apartindependently of the outer jaws to disengage the comb studs from theinstalled closure device.

FIG. 34A is an elevation view showing the handle of the applicator in anopen state.

FIG. 34B is an elevation view showing the handle of the applicator in anintermediate state.

FIG. 34C is an elevation view showing the handle of the applicator in afinal state, in which the jaws are first closed to install the closuredevice, and then the inner jaws are moved independently to disengage thecomb studs from the closure device.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides alternative and improved apparatus,systems, and methods for closing a tissue structure of a patient, forexample, a left atrial appendage in a patient at risk of stroke or otheradverse events resulting from emboli released into circulation from theleft atrial appendage. Patients benefiting from the procedures of thepresent invention will often be those suffering from atrial fibrillationwhich can cause clot and thrombus formation in the left atrialappendage, thus increasing the chance of emboli release.

The present invention provides a tissue closure device which is animplant introduced over the base of the tissue structure and left inplace to close the tissue structure at the base. The portion of thetissue structure which is over the base may then be excised or otherwiseremoved, although this may be left be left to the physician'spreference. The tissue closure device comprises a compression bodyhaving at least two opposed, compliant tissue-engaging surfaces whichwill be placed over opposite sides of the tissue structure. Thetissue-engaging surfaces will be held together by a plurality of axiallyspaced-apart tissue-penetrating fasteners which extend from one of thesurfaces, through the intermediate tissue, and into the other surface toboth hold the compression body in place and to apply a desired level ofcompression force, which is determined by both the softness of thecompression body and the distance between the surfaces when they arefully attached. A well may be provided in the compression body aroundthe tissue-penetrating barb of the fastener such that a gasket seal isformed by the compression body around the puncture site in the tissue. Astabilizing lip may be provided in one leg of the compression body toprevent a rolling motion of one leg with respect to another leg of thecompression body.

The compression force applied by the closure device can be varied, forexample, by controlling the distance between the surfaces and/or byproviding one or more barbs, detents, or other spaced-apart attachmentpoints which permit the tissue-engaging surfaces to be “ratcheted”together. In this way, the tissue-engaging surfaces can be closed with apredetermined closure force, as described below, with the resultingspacing between the tissue-engaging surfaces varying to accommodatetissue structures having different widths. That is, tissue-engagingsurfaces of the closure device will be closed with the predeterminedforce until such point that the tissue is deformed with a counter forcethat holds the tissue-engaging surfaces apart. The fasteners will thenlock in at the attachment point which most closely approximates thisspacing between the tissue-engaging surfaces. Typically, there may befrom 1 to 20 attachment points along the length of the fastener,typically from 2 to 8 attachment points, although in special cases, morethan 20 attachment points will be affixed. Other, non-lineararrangements of fasteners can also be used. A particular advantage ofthe fastener structure is that the fasteners will preferably neverextend beyond the exterior perimeter of the compression body afterdeployment. While the penetrating fasteners will be able to penetratetissue, they will not be able to penetrate outside of the compressionbody to place adjacent tissue structures at risk.

A particular advantage of the compression body of the present inventionis that it provides an “interrupted” attachment of the conformablesurfaces on either side of the appendage or other tissue structure,which is similar to closure with “interrupted suture.” Prior closuredevices, such as loops, lassoes, staples, and the like, can provide avery tight and hemostatic seal, but the seal is often too tight andtraumatic and will cause tissue necrosis at the closure region at thebase of the structure. The use of the tissue fasteners which arespaced-apart and bridged only by a soft compliant tissue-engagingsurface will provide an adequate hemostatic seal while at the same timesignificantly reducing the risk of tissue necrosis within the sealedregion, applying the same closure effectively as “interrupted suture.”The soft compliant tissue engaging surface functions to tack down thelayers of tissue between the seal, as well as to provide the spacingrequired between male and female fasteners. The combination of the softcompliant tissue engaging surface and the properly spaced apartfasteners result in little or no necrosis and erosion in the compressedtissue and its surrounding tissue areas, even in the dynamic environmentof a beating heart.

In some embodiments, however, tissue necrosis may actually be desirabledistal to the closure device, and it is possible to control tissuenecrosis by varying the durometer of the compliant material used in thebody of the device or by baffling the body material itself to allowhollow or open areas to add to its softness. Also, the amount of tissuenecrosis may be controlled by increasing or decreasing the spacingbetween the fasteners on each side of the device, and by increasing ordecreasing the installed distance between the male and female fasteners.

The compliant surfaces of the compression body will typically have adurometer in the range from 3 shore A to 15 shore A, more preferablyfrom 3 shore A to 5 shore A. Suitable materials for the compliant tissueengaging surface portions of the compression body include silicone,polyurethane, and other soft, biologically compatible polymers. The useof such soft materials provides a three-dimensional compliance so thatthe tissue-engaging surfaces will conform to the three-dimensionaltopography of the tissue after it has been compressed as describedabove, and averts the potential to cause significant damage to thepatient's tissue due to compliance mismatch. It is preferred that thecompliance of the compression body, or at least the tissue engagingsurfaces of the compression body, matches the compliance of the tissueto which the closure device is applied. Moreover, the installed closuredevice will preferably behave dynamically in the same manner as thepatient's tissue surrounding the device. For example, the density andflexibility of the compression body material, the amount of materialused for the compression body as compared to the number of rigidfasteners, the geometric configuration of the fasteners within thecompression body, the installed distance between male and femalefasteners (affecting the amount of compression placed on the interveningtissue), and the existence of any framework material interconnecting thefasteners in the compression body may all contribute to the dynamicperformance of the device.

In the exemplary embodiments described hereinafter, the compressionbodies may be composed entirely of the soft polymeric body material andthe fastener components which are described below may be composedentirely of rigid materials. It will be appreciated, however, that thecompression body could also have rigid frame, scaffold, or othercomponents forming a portion of the body which is left in place as theimplant. It is necessary only that the tissue-engaging surface of thecompression body be formed from a compliant material which allows localconformance of the compression body to the tissue surface being engaged.

In some instances, it may be desirable to form all or a portion of thecompression body from a biodegradable material. Certain biodegradablepolymers, such as polylactic acids (PLA's), polyethyl glycol (PEG's),and polyglycolic acids (PGLA's) can be formulated to have both suitabledurometers and to also to degrade in the thoracic or other bodyenvironment into which they are being implanted. Usually, it will bedesirable to have the implant remain in a structurally competent formfor a period of at least several weeks before significant degradationwould occur. After that time, healing of the punctured tissue (e.g., theleft atrial wall) will occur and the presence of the implant may nolonger be necessary. When employing such a biodegradable compressionbody, it will also be desirable to have the tissue-penetrating fastenersformed from a biodegradable material, such as a suitable biodegradablepolymer or possibly a biodegradable metal, such as an iron or steelfastener which will oxidize over a pre-selected time period.

The compliant and flexible compression body will usually comprise a pairof parallel, opposed legs having the tissue-engaging surface (usuallyplanar) on a side of each leg. Parallel opposed legs may be joined atboth ends, to form a continuous ring structure, at only one end, or atneither end, where they would be joined only after deployment of thetissue-penetrating fasteners after the member has been placed around theappendage or other tissue structure. In other instances, however, theopposed tissue-engaging surfaces could have non-parallel and/ornon-planar surfaces. For example, the tissue-engaging surfaces could becurved, usually being concave so that there is an open space surroundedby the surfaces when the legs are brought together. Alternatively, thesurfaces could be curved and convex so that the legs of the closuredevice will apply a greater force in the center than at the ends. In onealternative embodiment, the surface could employ an “ice cream scoop” 3Dconfiguration in which the tissue engaging surfaces grab a sphericalvolume of tissue. Still further alternatively, the surfaces could beirregular or have any one of a variety of other particular geometries.

In another aspect of the present invention, the compression body furthercomprises a vacuum plenum, preferably within each leg of the compressionbody. The vacuum plenum will typically open up into a plurality of portswhich will be engaged against tissue prior to deployment of thetissue-penetrating fasteners. The applied vacuum will help hold theclosure in place and conform tissue in a desired manner relative to thecompliant tissue body prior to final attachment of the compression body.Usually, the vacuum ports will be formed along a lower set face of theparallel legs, where the lower face is oriented at an angle relative tothe vacuum ports. Typically, the lower face may be orientedperpendicularly relative to the direction of actuation of thetissue-penetrating fasteners. In other instances, however, the vacuumports could be aligned in parallel with the direction of actuation ofthe fasteners, or could be aligned at virtually any other relativeangle. In this way, the lower face of the compression body may beengaged against the base of the left atrial appendage or other tissuestructure and held in place by the vacuum. Once the proper positioningof the compression body is confirmed, the vacuum will continue to holdthe compression body in place while the tissue fasteners are deployedthrough tissue and permanently affix the legs of the compression bodytogether.

The tissue-penetrating fasteners typically comprise male and femaleconnectors aligned along the opposed tissue-engaging surfaces.Alternatively, the fasteners may comprise barbed needles which arealigned upon at least one of the tissue-engaging surfaces. Thetissue-penetrating fasteners will, after deployment, preferably bespaced-apart by a distance of at least about 1 mm, preferably at leastabout 1.3 mm, and more preferably in the range from about 1.3 mm to 5mm, and most preferably in the range from about 1.3 mm to 2.6 mm.Usually, there will be only one line of tissue-penetrating fastenersdeployed from the compression body. In other instances two or moreparallel lines of fasteners might be employed. The line of fasteners caninclude 1 to 20 fasteners, more usually 2 to 8 fasteners. Also, thefasteners could be aligned along either or both faces of thetissue-engaging surfaces in a zig-zag or other non-linear manner,appreciating however that they must extend over an axial length on eachface, typically being at least about 2 mm, preferably at least about 5mm, more preferably at least about 10 mm, and most preferably in therange from about 10 mm to 40 mm. Materials for the tissue penetratingfasteners include but are not limited to a titanium grade 5 or astainless steel 316 LVM fastener or nitinol or ULTEM (which may beinjection molded).

In another aspect of the present invention, systems for closing a tissuestructure include a closure device in combination with a closure deviceapplicator. The closure device applicator detachably secures and opensthe closure device in order to place the closure device over or aroundthe tissue structure. The closure device also includes a plurality offasteners as generally described above. The closure device applicatormay be inserted into a port or lumen of the fasteners or may be usedwith an alignment comb that engages the fasteners of the closure device.The closure device applicator may include a vacuum path which connectsto the vacuum plenum within the closure device or applying a vacuum theclosure device and the tissue structure when the device is over thetissue structure.

The closure device applicator generally includes an jaw mechanism whichincludes two probes or jaws. Each probe is adapted to detachably engageone leg of the compliant compression body, using either an alignmentcomb received by the probe or by inserting the probe into a port orlumen which opens into the vacuum plenum of the compression body. Thus,probes of the jaw mechanism can serve to physically support and holdopen the closure device during deployment and to close the closuredevice and securely install the device into the tissue. The probes mayalso provide a vacuum to the compression body when it is desired toadhere the compression body to tissue prior to deployment of thefasteners.

The fasteners of the closure device will typically “float” within thecompression body, with the probes or jaws of the closure deviceapplicator providing the force necessary to push the fasteners together.In some instances, however, the fasteners may be linked by frames,wires, tethers, chains, or other interconnections in order to helpcontrol or limit movement of the fasteners before, during, or afterdeployment by the applicator. For example, the links could controlspacing between adjacent fasteners or control the horizontal and/orvertical alignment of the fasteners. In one method of manufacturing theclosure device, the fasteners may be injection molded from a harderthermoplastic such as ULTEM to a set spacing and length, for example, 6fasteners that are 0.26 mm apart. Subsequently, the soft compressionbody could be injection molded over two sets of the 6 injection moldedULTEM fasteners to form a C shaped closure device connected at one endand free at the opposite end.

In another aspect of the present invention, a method for closing a leftatrial appendage or other tissue structure comprises positioning acompression body over the tissue structure with at least two complianttissue-engaging surfaces engaging opposite sides of the structure.Preferably, the surfaces will be closed over the appendage or othertissue structure with a pressure sufficient to provide hemostasis andsealing but without causing tissue necrosis, typically being in therange from 0.25 psi to 20 psi, preferably in the range between 0.25 psiand 1.5 psi. The compression body may be initially held in place byapplying a vacuum through the compression body to adhere thetissue-engaging surfaces to the tissue structure, preferably to tissuesurrounding the base of the tissue structure. After proper positioningof the compression body is confirmed, the fasteners are deployed from atleast one of the tissue-engaging surfaces, through the tissue, and intothe other of the surfaces to close the tissue structure.

Positioning the compression body typically comprises advancing thecompression member via an open procedure or intercostally, i.e., betweenribs, preferably between the ribs 3 and 4. Usually, the compressionmember will be held on the applicator described above, with theapplicator first spreading the tissue-engaging surfaces so that thecompression body may be placed over or around the tissue structure andpositioned at the base of the tissue structure. After the positioning iscompleted, the legs of the compression body will be closed over thetissue (at a spacing to accommodate the thickness of the tissuetherebetween). Optionally, the vacuum may be applied while thecompression body is manipulated in order to assure proper positioning ofthe compression body and spreading of the tissue between the opposedtissue-engaging surfaces so that the pressure applied to the tissue isgenerally uniform along the length to be fastened.

The compression bodies will typically be positioned and/or attachedusing fasteners while the physician views a tissue structure through anoptical scope during at least a portion of the procedure. Alternatively,the physician could directly view the tissue structure through apercutaneous opening, typically the same percutaneous opening that canbe used to introduce the device applicator. The tissue closure device isdelivered via a clamping tool or device application that has a set ofprobes or jaws that come together in either a scissor action or inparallel motion. The jaws are activated by an external force applied bythe operator, which can be as a squeezing action, trigger action,push-pull action, or the like, on a handle of the device applicator. Thejaws may also incorporate mechanical advantages such as a cam or arcthat effectuates a linear “all at once” force that snaps all of thefasteners together simultaneously or in sequence.

Optionally, the vacuum applicators and plenums may be used to deliversubstances to the tissue structure through the compression body. Forexample, after the fasteners have been delivered, the vacuum can beturned off and a therapeutic or other agent delivered through the lumensand plenums so that it is released from the compression body in theregion of the base of the tissue structure. Exemplary substances whichcould be delivered include antibiotics, antiseptics,anti-inflammatories, anti-bacterial, and the like.

After all steps of the present invention have been generally completed,as described above, it is left to the medical professional whether toexcise the left atrial appendage or other tissue structure at a locationabove the compression body. Additional uses for the present inventioninclude efficient intravascular or extra-vascular clipping of ananeurysm sac or extra flesh during a tummy tuck, a stomach staplingprocedure, a lung reduction procedure, or a bowel resection procedure. Apronged formation or star shaped deployment of the compression bodiesmay be used to encourage efficient bunching of tissue. Another approachutilizes a single-fastener closure device, which consists of onefastener surrounded by a soft compression material in a pillow-likestructure. The single-tissue compression body may be utilized inprocedures where a single point closure device is needed, such as in afemoral closure procedure or in a fallopian tube or a bile duct closureprocedure. This single-fastener closure device effectively clamps offflow or shuts the tubular structure with out causing traumatic necrosis.A detailed description of the embodiments of the present invention withrespect to the figures is set forth below.

Referring now to FIG. 1, a tissue closure system 10 in accordance withan embodiment of the present invention includes a tissue closure device12 (shown in broken line) and a tissue closure applicator 14. The tissueclosure device 12 is removably held on a pair of probes 16 located atthe distal end shaft of 18 which is connected to a handle 20 at itsproximal end. As will be described in more detail with references toFIG. 9-13, the probes 16 will be spreadable, i.e., either in a parallelfashion or in a pivotal fashion, and will be able to apply a vacuum, oralternatively an infusion source, through the tissue closure device 12.To that end, a port 22 is provided on the handle 20 for connection tothe vacuum or infusion source. Additionally, the handle 20 comprises atrigger 24 which may be manually actuated in order to spread the probes16 to facilitate delivery over the target tissue structure, as will bedescribed in more detail below.

Referring now to FIGS. 2-4, which illustrates an embodiment of thetissue closure device in accordance with the present invention. Inparticular, tissue closure device 12 comprises a compression body 30,typically formed from silicone or other soft polymer. The compressionbody 30 comprises a pair of legs 32 and 34 having opposedtissue-engaging surfaces 36 and 38, respectively. Plenums 40 and 42 eachterminate at an opening or port 44 and 46, respectively, which portreceives one of the probes on the tissue closure applicator used inconnection with the present embodiment. A plurality of fasteners will beprovided in each of the legs 32 and 34, where the fasteners are adaptedso that they will engage and couple each other when the closure device12 is squeezed over tissue by the tissue closure applicator. As bestseen in FIG. 4, a series of spaced-apart male fasteners 50 are alignedin leg 32 so that sharpened tips 52 may be advanced laterally into theopening between surfaces 36 and 38. Similarly, a series of axiallyspaced-apart female fasteners 54 are arranged in leg 34 to receive themale portions of fasteners 50 when the applicator probes are squeezedtogether. As best shown in FIGS. 5A and 5B, the sharpened tip 52 has anannual groove 56 which is received and locked over a shoulder 58 formedin the female fastener 54. In this way, spacing between the opposedtissue-engaging surfaces 36 and 38 can be carefully controlled at adistance selected to provide proper compression while reducing the riskof tissue necrosis.

As shown in FIG. 5C, the female fasteners 54 may have a plurality ofshoulders 58 formed along their lengths in order to accommodate thegroove 56 of the male fastener 50 at a variety of depths. Thus, thefasteners 50 and 54 can accommodate tissue having different thicknesseswith essentially the same compression force.

As additionally seen in FIGS. 2-4, the tissue compression devices willhave a plurality of vacuum ports 60 formed over the lower surface 62thereof. These vacuum ports 60 communicate with the plenums 40 and 42 sothat vacuum applied in the plenums will draw against tissue beneath thetissue closure device 12. In this way, the tissue closure device 12 canbe initially adhered to tissue prior to actuation of the fasteners inthe device. The physician can manually reposition the closure deviceusing the tissue closure applicator, turning on and off the vacuum asnecessary, until the tissue is contacted as close to the base of theleft atrial appendage or other tissue structure as possible.Additionally, the tissue can be adjusted so that folds and surfacediscontinuities are minimized so that when the tissue closure 12 isclosed and the fasteners deployed, the tissue between thetissue-engaging surfaces will be relatively smooth and the pressureapplied will be relatively constant over the tissue surfaces. In thisway, the risk of tissue necrosis is further diminished.

Referring now to FIGS. 6-8, different embodiments of the tissue closuredevice of the present invention will be described. In FIG. 6, a tissueclosure device 2012 comprises first and second legs 2032 and 2034 havingports 2046 which are constructed generally as described above withrespect to tissue closure device 12. In contrast to tissue closuredevice 12, however, the device 2012 will not be formed as a continuousring, but instead will be two legs 2032 and 2034 which are joined attheir base but which are unattached at their distal end 2036. Tissueclosure device 2112, illustrated in FIG. 7, also includes first andsecond legs 2132 and 2134, respectively, which are generally the same aslegs 32 and 34 in tissue closure device 12. In contrast to the twoprevious embodiments, however, tissue closure device 2112 is joined atits distal end 2136 but is not joined at its proximal end 2140. Finally,a fourth embodiment is shown in tissue closure device 2212 in FIG. 8.Tissue closure device 2212 includes a first leg 2232 and a second leg2234, where the legs are not joined so that the tissue-engaging surfaces2236 and 2238 are completely free of each other and only joined by thetissue fasteners after deployment through tissue.

Referring now to FIGS. 9-11, a mechanism for laterally actuatingparallel probes 16 at the end of shaft 18 of the tissue closureapplicator 14 will be described. The proximal end 70 of each probe 16 isformed with an L-shaped structure having gear teeth 72 along each base70. A rotary gear 74, which is disposed in shaft 18, is disposed betweenthe teeth 72 to form a rack-and-pinion structure, as best seen in FIG.11. Thus, rotation of the shaft 74 in a first direction causes the probe16 to move apart in a parallel fashion, while rotation in the oppositedirection causes the probe 16 to move together in a parallel fashion.Rotation of the gear 74 can be effected by the trigger 24 on handle 20in a conventional manner. As also seen in FIG. 10, vacuum passages 80 ineach probe 16 are connected through open ends 19 to ports 82 in order tosupply a vacuum or provide infusion to the plenums 40 and 42 in thetissue closure device 12. Connecting tubes 17 from the shaft 18 providethe necessary connectors to a lumen in the shaft. Usually, the ports 82will be aligned with the ports 60 to provide for direction applicationof the vacuum or infusion.

Referring now to FIGS. 12 and 13, an alternate probe actuation mechanismwill be described. Probes 116 will be constructed generally the same asprobe 16, as illustrated in FIG. 10, but will be attached at theirproximal ends by a pivot assembly 90. The pivot assembly 90 includes areciprocating rod 92 which is attached by a pivot pin 94 (FIG. 13) tothe proximal ends of a pair of wing members 96. The distal ends of thewing members 96, in turn, are pivotally attached to lateral extensions98 of the probes 116. The probes 116 are pivotally attached at a pivotpin 100 which is disposed on a distal end of the apparatus shaft 118.Thus, by axially reciprocating the rod 92 in a proximal direction, asshown by arrow 102 in FIG. 13, the distal ends of the wing members 96will be closed inwardly, thus closing the probes 116, as shown in brokenline in FIG. 13.

Referring now to FIGS. 14-16, use of the tissue closure system of thepresent invention is illustrated with respect to a procedure forimplanting a tissue closure device about the base of a left atrialappendage LAA. The tissue closure device 2212 illustrated in FIG. 8mounted on the tissue applicator 14 is illustrated, but it will beappreciated that any of the other tissue closure devices illustratedherein may be used with its respective applicator. For example, closuredevice 12 may be used with applicator 14. The procedure may be performedthoracoscopically using a thoracoscope (not illustrated) which isintroduced in the region above the left atrial appendage LAA after theleft lung has been deflated. Alternatively, the procedure can beperformed under direct vision through the same incision through whichthe shaft 18 is introduced or through a separate incision formed overthe region of the left atrial appendage. In at least most if all cases,the patient's heart will remain beating during the procedure.

The shaft 18 of the tissue closure applicator 14 is introducedintercostally, typically between the third and fourth ribs and advancedtoward the patient's heart. The probes 16 are then spread apart,spreading the legs 2232 and 2234 of the closure device 2212 apart asshown in FIG. 14. After the legs are located on opposite sides of theleft atrial appendage LAA, the legs will be pressed downwardly on to thecardiac tissue surrounding the base of the appendage. The vacuum maythen be optionally applied through the legs 2232 and 2234, adhering thelegs to the cardiac surface. The shaft 18 may still be manipulated inorder to assure that the legs 2232 and 2234 are in a proper position.After the proper position is visually confirmed, the probes 16 will bemechanically closed, as illustrated in FIG. 15. The closure of the legsover the base of the left atrial appendage LAA will again be visuallyassessed. If it appears to be properly closed, with the legs firmlypressed upon the cardiac tissue at the base and the tissue of the basebeing compressed without excessive folding or other discontinuities, thetrigger 14 may be pulled in order to deliver the fasteners 50 into thefemale receptacles 54, as illustrated in FIG. 5B. At that time, thetissue closure applicator may be withdrawn, pulling the probes from thetissue closure device 2212. The tissue closure device 2212 is then leftin place at the base of the left atrial appendage LAA, as best shown inFIG. 16. Usually, the portion of the left atrial appendage above theclosure device 2212 will then be excised.

As illustrated in FIG. 17, the tissue closure device 2212 can beintroduced from other directions, such as from under the clavicle toapproach the left atrial appendage LAA from the top. The apparatus andprocedures of the present invention could also be used in open surgicalprocedures, although many of the benefits associated with least invasiveapproaches would be lost. The most important elements of the method forclosing the LAA using the present system are 1) correct placement of thedevice at the ostia to ensure a smooth inner closure site inside theleft atrium, 2) staying off the wall of the left atrium to avoidoccluding the circumflex artery, 3) creating total occlusion of theclosure site, 4) eliminating suture line bleeding, and 5) choosing thecorrect closure device softness and compliance to eliminate erosion ofthe surrounding tissue.

FIGS. 18-20 illustrate another embodiment of the tissue closure devicein accordance with the present invention. Tissue closure device 1800includes a compression body 1810 formed from silicone or another softpolymer. Compression body 1810 includes opposing legs 1820 and 1830having opposed tissue engaging surfaces 1822 and 1832. A plurality offasteners are provided in each of the legs 1820 and 1830. As best seenin FIG. 19, a plurality of spaced-apart male fasteners 1824 are disposedwithin leg 1820 and corresponding female fasteners 1834 are disposedwithin leg 1830. As best seen in FIG. 20, leg 1820 includes astabilizing lip 1826 extending along its entire length that helps toensure equal pressure at the puncture site and prevent rollingdisplacement of leg 1820 out of its shared plane with leg 1830.

Referring to FIG. 20, male fastener 1824 includes needle barb 1825having a sharp tip 1828 configured to pierce through tissue disposedbetween surfaces 1822 and 1832. Barb 1825 may include an annual groove1825 a that may be used to snap the barb into place inside the femalefastener 1834. Around each barb 1825, the compression body of leg 1820includes a well 1829 surrounding the barb in which the silicon materialis removed. The diameter of well 1829 may be slightly larger than thediameter of barb 1825 such that the compression body around the welldoes not contact barb 1825 in an initial state. Well 1829 enables thebarb 1825 to more freely translate in the vertical direction andcontributes to the compliance of the surrounding compression body, whichis less bound by friction to barb 1825 and more free to deform and moverelative to the barb. Male fastener 1824 also includes a recess 1827 atits rear configured to create a snap fit connection with studs of theactuating comb, details of which will be discussed below. Wells 1827 aare provided at the top of leg 1820 corresponding to each recess 1827 soas to allow the studs of the actuating comb to be inserted into recess1827.

Female fastener 1834 includes a cone shaped needle barb acceptor 1836, aneck 1838, and a recess 1837. Acceptor 1836 is shaped so as to guide thetip 1828 of needle barb 1825 into the female fastener. Wells 1836 a areprovided in the surface 1832 of the compression body corresponding tothe location of each acceptor 1836 to enable passage of barb 1825 intothe female fastener. Well 1836 a may be of the same diameter as well1829. Well 1836 a enables the barb 1825 to pass directly into the femalefastener 1834 and improves the compliance of the compression bodysurrounding the barb after it has been installed. Wells 1836 a and 1829also operate in concert to create a gasket seal around the puncture siteof the tissue. Once the fasteners are installed, the puncture site wherebarb 1825 has punctured the tissue is surrounded by well 1829 on oneside and by well 1836 a on the opposing side. The gasket seal capturesthe blood that may be released from the puncture site and prevents theblood from escaping the device. Moreover, the overall amount of bleedingmay also be decreased by the pressure placed on the puncture site by thegasket seal.

Neck 1838 of the female fastener may have a diameter that is conducivefor creating a snap fit when barb 1825 is inserted into female fastener1834. For example, sharp tip 1828 of barb 1825 may pass through neck1838 until a rear shoulder of the tip passes into recess 1837 andretains the barb 1825 in place. Recess 1837 of the female fasteneraccommodates the actuating comb of the present invention, which will bediscussed in more detail below. Access through the compression body torecess 1837 is provided through well 1837 a in the compression body thatcorresponds to each female fastener 1834.

FIG. 21 provides a rear perspective view of male fastener 1824 detailingrecess 1827 at its rear and barb 1825 protruding toward the front. Barb1827 includes sharp tip 1828 and annualized groove 1825 a. FIG. 22provides a front perspective view of fastener 1824 detailing the mannerin which barb 1825 protrudes from male fastener 1824. FIG. 23 provides across-sectional view of male fastener 1824 showing that barb 1825 may bea separate element embedded into the rear portion of fastener 1824. FIG.24 provides a front perspective view of female fastener 1834 detailingrecess 1837. FIG. 25 provides a rear perspective view detailing barbacceptor 1836 and neck portion 1838. FIG. 26 is a cross-sectional viewof female fastener 1834 showing its interior construction.

As mentioned previously, an alignment comb may be used with the closuredevice in an embodiment of the present invention. In particular, theclosure device may be loaded onto a pair of opposing alignment combs tofacilitate alignment between the male and female fasteners duringinstallation. Referring to FIG. 27, each alignment comb 2700 includes anumber of comb studs 2720 disposed on a body 2710. The number of studs2720 in each comb corresponds to the number of fasteners pairs used inthe tissue closure device to be installed. Body 2710 includes a dowelhole 2712 that may be used to secure the comb 2700 into an applicator ofthe present invention (detailed below). Stud 2720 is configured to beinserted into recesses 1827 and 1837 of the fasteners.

As shown in the detailed view of FIG. 28, each stud 2720 is shaped as anoval in cross section so as to enable uniform orientation of thefasteners when the stud 2720 is inserted into the similarly oval shapedrecess 1827/1837. Each stud 2720 is further configured with a taper,such that the cross section of the stud is smaller at the tip than atthe base, to facilitate a “snap-fit” connection with the recesses1827/1837. That is, the taper enables studs 2720 to be easily insertedinto recesses 1827/1837 to create a friction fit, and also enable thestuds to be more easily disengaged from the recesses once installationof the device is complete. Stud 2720 further includes a hollow interiorchannel 2722 configured to allow barb 1825 to pass into recess 1837 ofthe female connector 1834 when the stud 2720 is engaged with the femaleconnector.

FIGS. 29 and 30 illustrate how the “snap-fit” connection is used toinstall the tissue closure device. FIG. 29 shows a number of spacedapart male fasteners 1824 of a leg 1820 loaded onto an alignment comb2700 (the compression body of leg 1820 has been omitted for sake ofclarity). The friction fit between studs 2720 and recesses 1827 issufficient to securely hold fasteners 1824 on the comb during theinstallation procedure. Studs 2720 are used to apply the installationforce 2910 to fasteners 1824 so as to press the male fasteners securelyinto place within the female fasteners. After the installation iscomplete, FIG. 30 illustrates how the fasteners 1824 are ejected fromthe comb 2700 using a release force 3010 that does not endanger thesecure engagement between installed male and female fasteners.

The foregoing generally relates to a linear embodiment of the tissueclosure device in which the opposing pairs of fasteners 1824/1834 aregenerally disposed along a single line. Other, non-linear embodiments ofthe tissue closure device are contemplated by the present applicationand can be used to create flexible solutions to tissue closure problems.As shown in FIGS. 31A and 31B, a closure device 3100 includes a singlepair of opposing fasteners 1824/1834 disposed at the geometric center ofa compression body 3110. Compression body 3110 has a top portion 3120and a bottom portion 3130 with opposing surfaces 3122 and 3132. Top andbottom portions 3120 and 3130 may be interconnected or may beindependent bodies. Wells 3129 and 3136 a are disposed on the top andbottom portions, respectively, to provide for a gasket seal around thepuncture site. FIGS. 31C and 31D illustrate other alternative geometriesfor a tissue closure device. A single device with the correct geometrymay be selected or manufactured to provide a customized tissue closuresolution, or a combination of devices may be used to accomplish thesame.

FIG. 32 illustrates an applicator that may be used to install the tissueclosure device in accordance with an embodiment of the invention. Asillustrated in the FIG. 32, applicator 3200 is be loaded with closuredevice 1800 (using alignment combs 2700). The applicator 3200 includes ahandle 3250 that is movable relative to base 3252 to actuate jaws 3210.The applicator also includes an orientation hub 3254 and an outer shaft3260. FIG. 33A shows the applicator jaws 3210 in an open state. Inparticular, jaws 3210 include a set of inner jaws 3210 a that arecoupled to cam 3230 and capable of pivoting about the cam 3230 to closein a scissor-like manner. Cam 3230 is disposed within housing 3290 andis coupled to an inner shaft 3262 disposed coaxially within outer shaft3260. Jaws 3210 further include a set of outer jaws 3210 b that pivot atpoints 3282 on a base portion 3280, which is movable relative to ahousing 3290 and may be coupled to the outer shaft (not shown). Outerjaws 3210 b fit over inner jaws 3210 a and have substantially the sameposition in the initial, open state of the jaws. Outer jaws 3210 b mayinclude cut-away tracks 3214 for receiving a dowel pin 3212 used tosecure the alignment comb 2700 within the inner jaw 3210 a. As shown inFIG. 33A, an alignment comb 2700 is fitted into each of the inner jaws3210 a.

From the open position shown in FIG. 33A, the user actuates the handle3250 to cause inner shaft 3262 to retract into housing 3290 (in thedownward direction as shown in FIGS. 33A-C). This retraction causesinner jaws 3210 a to withdraw into housing 3290 and to abut against thesides of housing 3290, which causes the inner jaws 3210 a to close. Themovement of the inner jaws 3210 a causes a corresponding retraction andclosing of outer jaws 3210 b, as the motion is transferred through dowelpin 3212 and track 3214. As shown in FIG. 33B, jaws 3210 are retractedinto housing 3290 from the open position of FIG. 33A, and base portion3280 has moved downward relative to housing 3290. Jaws 3210, in theclosed state, cause the opposing comb studs 2720 to be disposed a setdistance apart, such that male fasteners 1824 and female fasteners 1834of the closure device 1800 loaded on the combs 2700 are securely engagedtogether. That is, by moving the jaws 3210 from the open state to theclosed state, barb 1825 of the male fastener 1824 is caused to movetoward opposing female fastener 1834, pierce the intervening tissue atthe puncture site, and become securely engaged with female fastener 1834(e.g., when sharp tip 1828 passes into recess 1837). Once the opposingmale and female fasteners of the closure device have been securelyengaged with each other, the successfully installed closure device isleft in place when the comb studs 2720 are disengaged from the recesses1827/1837 of the fasteners.

FIG. 33C illustrates one approach for accomplishing the disengagementmotion, in which the inner shaft 3262 is actuated upward to push cam3230 in the upward direction. Upward movement of cam 3230 causes theinner jaws 3210 b to move along track 3214 upward and outward so as torelease the comb studs 2720 from the recesses 1827/1837. This movementof inner jaws 3210 b is independent of outer jaws 3210 a. Movement ofcombs 2700 in a direction opposite to the direction of installationcauses comb studs 2720 to disengage from the recesses 1827/1837 andfrees the installed closure device 1800 from the applicator.

In some embodiments, a lasso wire may be deployed from an aperture inthe distal end of a first jaw 3210 to be received and secured in asecond aperture in the distal end of the other jaw 3210. The lasso wiremay be of a hemispherical shape when deployed and serves to constrainthe tissue to be secured between jaws 3210. In some instances, as jaws3210 come together to install the closure device, the intervening tissuemay experience a tendancy to slip toward the distal end of the jaws andout of the area between the jaws 3210. The lasso wire prevents suchmovement by the tissue. In some embodiments, jaws 3210 may be disposedin a plane offset from the plane of shaft 3260 by a predeterminedrotation. The plane of jaws 3210 may be offset from the plane of shaft3260 by 10 to 45 degrees, and preferably by 10 to 25 degrees.

FIGS. 34A-C illustrate how the handle portion of the applicator 3200actuates the jaws 3210. FIG. 34A shows an initial position of the handleportion in which jaws 3210 are open (as shown in FIG. 33A). Outer shaft3260 is keyed to hub 3254 so as to enable rotation of the jaws about theaxis of shaft 3260 when hub 3254 is rotated. Shaft 3260 is, however,slideable relative to hub 3254 along the axis of the shaft. Inner shaft3262 is disposed coaxially within outer shaft 3260 and is coupled totrunnion 3270, which may be spring-biased to its current position.Handle 3250 is coupled to trunnion 3270 via link 3255. Handle 3250 mayalso include a spring biased arm 3280 that is biased downward to contactthe upper surface of trunnion 3270. When handle 3250 is pulled back andactuated, trunnion 3270 and inner shaft 3262 are caused to retract (tothe right in FIG. 34B), and by transferred movement of the inner jaws3210 a to the outer jaws 3210 b, outer shaft 3260 (coupled to the outerjaws 3210 b) are also caused to retract by a corresponding displacement.As shown in FIG. 34B, spring-biased arm 3280 enters a series of ratchetteeth 3272 disposed on the top surface of trunnion 3270, which preventsthe trunnion from returning to its spring-biased position of FIG. 34A.Prior to engaging teeth 3272, displacement of the trunnion 3270 causedby the actuation of handle 3250 are undone when handle 3250 is released.As shown in FIG. 34C, handle 3250 is then pulled to its final positionto install the closure device by moving arms 3210 together (as shown inFIG. 33B). In this position, inner shaft 3262 and outer shaft 3260 areat their rearmost position. Locking plate 3264 is used as a one wayclutch to secure outer shaft 3260 at its rearmost position. As shown inFIG. 34C, arm 3280 has now exited the ratchet teeth 3272, which enablesspring-biased trunnion 3270 to move forward along with coupled innershaft 3262. This forward movement of the inner shaft 3262 independent ofouter shaft 3260 actuates the movement of inner jaws 3210 a independentof outer jaws 3210 b, as shown in FIG. 33C.

While the above is a description of the preferred embodiments of theinvention, various alternatives, modifications, and equivalents may beused. Therefore, the above description should not be taken as limitingthe scope of the invention which is defined by the appended claims.

What is claimed is:
 1. A method for closing a tissue structure, saidmethod comprising: positioning a compression body over the tissuestructure with at least two compliant tissue-engaging surfaces engagingopposite sides of the structure; applying a vacuum through thecompression body to adhere the surfaces to the tissue structure; anddeploying fasteners from at least one of said surfaces, through thetissue, and into the other surface to close the tissue structure whilethe vacuum continues to be applied.
 2. A method as in claim 1, whereinthe tissue structure is a left atrial appendage.
 3. A method as in claim2, wherein positioning comprises intercostally advancing the compressionmember.
 4. A method as in claim 2, wherein positioning comprisescarrying the compliant compression body on an applicator, spreading thetissue-engaging surfaces using the applicator, and closing the spreadlegs over the tissue structure before applying the vacuum.
 5. A methodas in claim 1, wherein deploying fasteners comprises advancing maleelements from either or both of the tissue-engaging surface(s) to femaleelements in the opposed tissue-engaging surface.
 6. A method as in claim1, wherein deploying fasteners comprises advanced barbed needles fromone tissue-engaging surface to the other tissue-engaging surface.
 7. Amethod as in claim 1, further comprising viewing the tissue structurethrough an optical scope during at least a portion of the procedure. 8.A method as in claim 1, further comprising directly viewing the tissuestructure through a percutaneous opening during at least a portion ofthe procedure.
 9. A method as in claim 1, further comprising introducinga substance to the tissue structure through the compression body.
 10. Amethod as in claim 9, wherein the substance is an antibiotic, anantiseptic, or an anti-inflammatory.
 11. A method as in claim 1, furthercomprising excising the tissue structure at a location above thecompression body after the fasteners have been deployed.
 12. A method asin claim 1, wherein the fasteners do not extend out of the compressionbody after deployment.
 13. A method as in claim 1, wherein the fastenersare deployed to close the tissue-engaging surfaces against the tissuewith a pressure in the range from 0.25 psi to 20 psi.
 14. A method as inclaim 13, wherein the pressure is in the range from 0.25 psi to 1.5 psi.